Q) Explain the formation of depletion layer and potential barrier in a p-n junction ?
Q) Explain the formation of depletion layer and potential barrier in a p-n junction ?
Hi Sanal!
When a P-N junction is formed, the majority carriers at both sides near the junction diffuse to the opposite side. That is, electrons from the N-side diffuse towards the P-side and holes from the P-side diffuse towards the N-side. This diffusion leaves behind ionized donors on the N-side and ionized acceptors on the P-side. The ionized donors and acceptors are immobile, as they are bonded to the surrounding atoms of the crystal lattice. This layer of immobile ions is known as depletion region or space charge region. That is, there are no free electrons or holes in this region. The thickness of the depletion region is of the order of one-tenth of a micrometer.
Due to this space charge region, an electric field directed from positive charge towards negative charge develops. This field gives rise to the flow of minority carriers. That is, holes in the N-side are attracted towards the P-side and electrons in the P-side are attracted towards the N-side. The motion of charge carriers due to the electric field is known as drift.
The diffusion and drift continues until there is no net current. The loss of electrons from the N-side and the gain of electrons by the P-side cause a potential difference across the junction. This potential prevents further movement of charge carriers and is called as barrier potential.
Cheers!!
Hi Sanal!
When a P-N junction is formed, the majority carriers at both sides near the junction diffuse to the opposite side. That is, electrons from the N-side diffuse towards the P-side and holes from the P-side diffuse towards the N-side. This diffusion leaves behind ionized donors on the N-side and ionized acceptors on the P-side. The ionized donors and acceptors are immobile, as they are bonded to the surrounding atoms of the crystal lattice. This layer of immobile ions is known as depletion region or space charge region. That is, there are no free electrons or holes in this region. The thickness of the depletion region is of the order of one-tenth of a micrometer.
Due to this space charge region, an electric field directed from positive charge towards negative charge develops. This field gives rise to the flow of minority carriers. That is, holes in the N-side are attracted towards the P-side and electrons in the P-side are attracted towards the N-side. The motion of charge carriers due to the electric field is known as drift.
The diffusion and drift continues until there is no net current. The loss of electrons from the N-side and the gain of electrons by the P-side cause a potential difference across the junction. This potential prevents further movement of charge carriers and is called as barrier potential.
Cheers!!
